Microwave oven



FIG. 1 is a front elevation view of a microwave oven;

FIG. 2 is a left side elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a perspective view thereof.

The broken lines represent unclaimed features that form no part of the claimed design. 

CLAIM The ornamental design for a microwave oven, as shown and described. 